Apparatus for individually separating heddles and like objects from a row preparatory to a drawing-in operation

ABSTRACT

Apparatus for individually and successively separating heddles from a row of heddles by means of an electromagnet which is moved towards the first heddle in a row to remove that heddle to a position in which a thread may be pulled through the heddle eyelet. During the first part of the movement of the magnet away from the heddle row, the magnet receives a relatively weak current ensuring that only one heddle is taken along, and when the heddle has been sufficiently detached from the remaining heddles in the row, the current is increased to increase the holding force of the magnet. Two or more heddles may be separated from different rows in one operation, preferably with a short time interval so that they will be moved to spaced drawing-in positions. The apparatus may also be used for separating drop blades and similar object preparatory to a drawing-in operation.

United States Patent 1 Fleischer et a1.

[ APPARATUS FOR INDIVIDUALLY SEPARATING HEDDLES AND LIKE OBJECTS FROM AROW PREPARATORY TO A DRAWING-IN OPERATION [75] Inventors: Svend SigurdChristie Fleischer,

Klampenborg; Knud Helge Jeppsson, Copenhagen, both of Denmark [73]Assignee: Titan Textile Machines A/S,

Metalbuen, Ballerup, Denmark 22] Filed: June16, 1972 21 Appl, No.:263,573

[30] Foreign Application Priority Data Dec. 11, 1973 PrimaryExaminer-James Kee Chi AttarneyFrancis C. Browne et a1.

[57] ABSTRACT Apparatus for individually and successively separatingheddles from a row of heddles by means of an electromagnet which ismoved towards the first heddle in a row to remove that heddle to aposition in which a thread may be pulled through the heddle eyelet.During the first part of the movement of the magnet away from the heddlerow, the magnet receives a relatively weak current ensuring that onlyone heddle is taken along, and when the heddle has been sufficientlydetached from the remaining heddles in the row, the current is increasedto increase the holding force of the magnet. Two or more heddles may beseparated from different rows in one operation, preferably with a shorttime interval so that they will be moved to spaced drawing-in positions.The apparatus may also be used for separating drop blades and similarobject preparatory to a drawing-in operation.

10 Claims, 5 Drawing Figures APPARATUS FOR INDIVIDUALLY SEPARATINGIIEDDLES AND LIKE OBJECTS FROM A ROW PREPARATORY TO A DRAWING-INOPERATION BACKGROUND OF THE INVENTION The present invention relates toan apparatus for individually separating heddles (or drop blades) from arow of heddles positioning a heddle for subsequent drawing-in of a warpthread from a warp through an eyelet of each heddle, which apparatus isprovided with a gripper magnet that is movable towards and away from therow of heddles.

In a loom, the heddles are mounted in two or more weaving shafts andthey serve to raise and/or lower the warp threads in accordance with theweave desired in the fabric whereby they form the so-called shed throughwhich the weft thread is introduced. When reference is made in thisspecification .and the appended claims to heddles this word is to beconstrued as covering also the so-called stop motion or drop blades orwarp detectors which, in a corresponding manner, are individuallydisposed the warp threads so as to render possible the stopping of theloom in the event of a warp thread. break.

It is known to utilize a permar'nent magnet mounted on a movable arm forseparating a heddle (or drop blade) from a row of heddles and foradvancing the heddle to a position spaced from the other heddles of throw for drawing-in a warp thread either'manually or mechanically. It hasto be ensured that the retaining force of the magnet is no greater thanis necessary for removing a'single heddle only from the row at a time,but this'entails a certain risk that during the movement of the magnettowards the drawing-in or heddling position the heddle is dropped forinstance if the frictional or other resistance against the movement ofthe heddle along the supporting rails of the weaving shaft varies. Thedifficulties are increased further 'by the circumstance that heddles mayhave varying thickness and varying material properties or they may bemore orless deformed in the area in which the magnet is to grip them. Amagnet having a holding force suitable for separating relatively thickheddles may, for example, often be inclined to take two heddles at atime, when it is employed with thinner heddles. Consequently, it has insuch cases been necessary to replace the magnets or, if possible, tochange their holding force by adjusting the distance between theirpoles. Both these solutions are,

however, complicated and time-consuming.

BRIEF SUMMARY OF THE INVENTION According to the invention there isprovided an apparatus for individually separating heddles and likeobjects, such as drop blades, from a row of heddles and positioning aheddle for subsequent drawing-in of a warp thread from a warp through aneyelet of each heddle, said apparatus comprising a gripperelectromagnet, means for moving said gripper magnet towards and awayfrom the row of heddles, and means for supplying said electromagnet witha relatively weak magnetizing current during the initial phase of itsmovement'away from the row of heddles, and with a relatively strongmagnetizing current during the subsequent phase of said movement.

The invention has the advantage that the reliability of the apparatus isincreased quite substantially by virtue of the fact that the separatingoperation is effected with It is'then possible to let the movement occurat a greater speed than according to the prior art since the retainingforce can be increased to such a value that net can be safelytransmitted to the heddle without any danger of the heddle being droppedfrom the magnet. The rate of operation of the apparatus can be steppedup in this way also because the strong magnetizing current can beswitched on already after a very short travel of the heddle away fromthe row of heddles, in practice a few millimetres, as an air gap of thissize effectively prevents magnetic attraction of the next heddle in therow.

The apparatus may comprise control means adapted to completely orsubstantially demagnetize the gripper magnet before it starts to moveback towards the remaining heddles in the row. The heddle, through whicha warp thread has been drawn, can then be readily pushed away from theheddling point because the magnet no longer exerts a holding force uponit. When the magnet is supplied with DC current, it is possible to Ibring about the demagnetization by reversing the direction of thecurrent through the magnet coil whereby any remanence in the grippermagnet and in the heddle is eliminated.

The control means may comprise a variable resistor for manual adjustmentof at least the relatively weak magnetizing current. While it will benormally possible to operate with a fixed or constant high value of thestrong magnetizing current, it is advantageous to be able, while theapparatus is in operation, to adjust the weak initial current, theoptimum value of which depends to a larger extent upon the heddlesemployed.

The gripper magnet may be mounted on an arm supported in a reciprocatingframe which is displaceable parallel to the row of heddles and which isprovided with actuating means for a stationary change-over switchadapted to alternately couple the magnet coil to one or the other of twoparallel feed or supply circuits for the electromagnet. It is achievedhereby that the change-over operation between the two different valuesof the magnetizing current always takes place at a specific point in thetravel of the magnet.

The frame may be provided with a pawl means adapted to couple it to areciprocating driving mechanism and to simultaneously close a switchforming part of both parallel supply circuits. The gripper magnet thenreceives current only during its movement so that, particularly in anapparatus having several magnets for separating heddles from acorresponding number of rows of heddles, the magnetization of thenonoperative, stationary magnets is avoided. Consequently, thenon-operative magnets do not consume current'and' do not magnetize theassociated heddles.

The driving mechanism of the frame may comprize an intermittentlyrotating drive shaft that carries a first cam adapted to close a switchcommon to both supply circuits, at least during the movement of theframe away from the row of heddles, and a second cam adapted to actuatea switch of a supply circuit for a magnet coil mounted in the frame andadapted to effect engagement of the pawl means with the drivingmechanism. Hereby an exact synchronization between the movement of thegripper magnet and the switching on an off of the magnetizing current isachieved.

In an embodiment of the apparatus which has a plurality of frames andassociated arms and gripper magnets for individually separating heddlesfrom a corresponding number of parallel rows of heddles, the apparatusmay be provided with a common driving mechanism for all the frames, thepawl means of each frame may be locked to the driving mechanism duringthe reciprocating movement of the mechanism, the second cam may beprovided with two angularly spaced areas for successively actuating itsassociated switch, and the apparatus may be equipped with a programmingdevice which connects the switch with the magnet coil of a selectedframe and which, during the period between the two actuation operationsof the switch, is advanced one step. It is then possible during eachfull revolution of the drive shaft which simultaneously acts as acontrol shaft to separate two heddles from their respective row ofheddles and to move them unequally away from the respective row,following which two warp threads may be drawn in through theirrespective heddle eyelet either simultaneously by means of a doubleheddling hook, or successively with a single heddling hook. Thispossibility contributes further towards increasing the rate of operationthat is attainable by the apparatus.

For effecting the demagnetization of the gripper magnet, as mentionedabove, by altering the direction of the magnetizing current, the driveshaft may carry a third cam adapted to reverse the polarity of thesupply circuit of the gripper magnet.

The drive shaft may carry a fourth cam designed in such a way as to,twice during a revolution of the shaft, actuate a change-over switchbetween two parallel supply circuits of an electromagnetic clutch whichforms part of the shaft drive, of which circuits one connects the magnetcoil of the clutch directly to a voltage source while the othercomprises a manually actuable switch. Hereby an automatic control of thefunctions of the apparatus by a pulse switch' is made possible, whichswitch may, for example, be incorporated into the heddling hook.

Additional characteristic features and advantages of the invention willbecome apparent from the following description and the accompanyingdrawings which, in a rather diagrammatical form, illustrate the detailsof an embodiment of the apparatus which are deemed sufficient andnecessary for understanding the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an end view of theapparatus mounted in connection with a plurality of weaving shafts and awarp beam, from which warp threads are to be drawn through the heddleeyelets of the shafts and provided with warp detectors or stop blades bymeans of the apparatus.

FIG. 2 shows an elevation of the heddles of a single weaving shaft withthe associated gripping magnet and a part of its driving mechanism,

FIGS. 3 shows a view corresponding to FIG. 2, in which the drivingmechanism has been omitted and where the gripper magnet has removed aheddle from the other heddles in the weaving shaft,

FIG. 4 shows a top plan view illustrating a part of the drivingmechanism for the gripper magnets of the apparatus, and

FIG. 5 shows a wiring diagram for illustrating the function of theapparatus.

DETAILED DESCRIPTION The apparatus illustrated in the drawings has acarriage I which is supported by means of wheels 2 so as to be movableon rails 3 above and parallel to (i.e., at right angles to the plane ofthe drawing of FIG. 1) a plurality of weaving shafts 4 which, in amanner not shown in detail, aresupported in a frame of which the rails 3form part.

Each weaving shaft is constructed as a frame, of which FIG. 1 shows thetopmost and the bottommost frame beam 5 and 6, respectively, and isprovided with two horizontal supporting rails 7 and 8 for the heddles 9.

The separating apparatus has, for each weaving shaft 4, a verticallydownwardly projecting arm 10 that carries a gripper magnet 11 which isable to take a heddle 9 from the row of heddles supported by'theassociated weaving shaft and to convey it forward to the heddlingposition, cf. FIGS. 2-3. The apparatus has, moreover, a plurality ofarms 12, of which FIG. 1 shows only one, and each arm carries a grippermagnet 11 which, in a corresponding manner, is able to pull warpdetectors or drop blades 13 forward from a series of drop blades andposition a blade 13 in alignment with a heddle 9 which is separated withthe aid of a magnet 11 on one of the arms 10. 7

Behind the frame (not shown) which carries the weaving shafts, the dropblades and the separating apparatus, a warp beam 14 with a warp 15 issupported in an appropriate manner. The threads of warp 15 are passed,from warp beam 14, across a guiding roll 16 and, in a known manner, heldin a vertical position by means of a diagrammatically indicated threadclamp 17. An operator standing in front of the apparatus, that is to sayto the right-hand side of FIG. 1, can, with the aid of a heddling hook,take the warp thread 18 of the warp, which at any time is located at theedge of the warp and pass it through the eyelet 19 of drop blade 13 andfurtherthrough eyelet 20 of heddle 9 which assumes the heddlingposition. I

In timed relationship with the successive drawing-in of the individualwarp threads the carriage l is moved by means of a drive motor (notshown) along rails 3, whereby it is ensured, inter alia, that therespective gripper magnets 11 are always in contact with the foremostheddle or drop blade of the associated row through which a warp threadhas not yet been drawn in. Since the separation of heddles and dropblades takes place in principally the same, only the separation ofheddles 9 is described in the following.

Each of the vertical arms 10 is supported in a separate frame 21 ofcarriage l. A driving rod 22 extends lengthwise through each frame 21-,the two end walls of which are provided with hearing bores (not shown)for the rod. All driving rods 22 are, at their left-hand end, as seen inFIGS. 2 and 4, coupled to a common cross bar 23 which, via twoconnecting rods 24, of which FIG. 4 only shows one, is coupled to cranks25 provided on the extremities of a drive shaft 26 extending across andthrough carriage 1. Shaft 26 is supported in two bearings 27 rigidlyconnected with carriage l, and

cross bar 23 is guided in two guides 28 which may be shaped in such away that at the beginning of its movement towards the left from theposition shown in FIGS. 2 and 4, cross bar 23 is raised slightly,whereby frames 21 and carrying arms 20 are pivoted slightly in aclockwise direction (FIG. 2) which has the effect that a heddle 9 heldby a retaining magnet 11 is raised slightly from its supporting rails 7and 8. Driving rods 22 which, behind frames 21, are supported in bearingbores of a cross bar 29 of carriage 1, must in that case havesubstantial play in the bearing bores.

Drive shaft 26 is driven by a motor 30 via an electromagnetic clutch 31and a gear 32 which, in the embodiment shown, is made up of two gearwheels. For each revolution of shaft 26, cross bar 23 and frames 21 moveonce backwards and forwards in the longitudinal direction of the weavingshafts and, by means of the control circuit described below, one (orpossibly two) of the arms is mechanically coupled to the associateddriving rod 22 while the associated gripper magnet 11 is energized and,thereby, separates and removes a heddle 9 from the associated weavingshaft as shown in FIGS. 2 and 3.

Each driving rod 22 which, as mentioned, is ableto pass freely throughthe associated frame 21, is provided with two recesses 33 and 34, andthe frame has a pawl 35 secured to a spring arm 36 that is pivotable inthe frame. Upon energization of a magnet 37, the spring arm 36 will bepulled downwards whereby pawl 35 is brought into engagement with one orthe other of recesses 33 and 34 dependent upon the moment of actuationof the magnet so that frame 21 with arm 10 and magnet 11 moves togetherwith its driving rod 22. A mechanical locking mechanism (not shown) isprovided which, subsequent to the arrangementof the pawl, maintains itin engagement with the driving rod until the rod has returned toapproximately its startng position even if the current to electromagnet37 is switched off.

The magnetizing coil (not shown) of the gripper magnet 11 is connnectedbetween the frame of the apparatus and a wire 38'thatextendsupwardlythrough the hollow arm 10 and is connected to a switch 39mounted in frame 21, which switch is mechanically connected. to springarm 36 so that the switch connects wire 38 to a wire 40 when pawl 35 isin engagement with one of the recesses of driving rod 22. Wire 40 isconnected to a changeover switch 41 secured to carriage 1 so as to movetherewith and which during movement of frame 21 relative to the carriagemay be actuated by a roller 42 in engagement with an inclined surface 43on the top side of the frame 21. Change-over switch 41 is in theposition shown in FIG. 5 when frame 21 is in its rest position, but ischanged over into its other positon when frame 21, by means of pawl 35,has been coupled to driving rod 22 and thus moves towards the left ofFIG. 5. In the first-mentioned position, switch 41 connects wire 40 towire 44, the other end of which is connected to the adjustable tappingor contact arm of a potentiometer 45, from which a line 46 establishesconnection with a wire 47 which connects the second contact ofchange-over switch 41 to two interconnected contacts 48 and 49 of a gangor double changeover switch 50. From wire 47 a branch line 51 isconnected to the above-mentioned magnet 37, the other power supply line52 of which is connected to a movablecontact pin 53 which interacts witha punched tape 54. It will be seen from FIG. 5 that tape 54 has alongitudinal row of perforations 55 and an associated contact pin 53 foreach gripper magnet 11 of the apparatus.

The change-over switch 50 mentioned above has input terminals 56 and 57connected to the plus and minus pole, respectively, of a voltage sourcefor supplying DC current to the above-mentioned magnets 11 and 37.Besides the two output terminals or contacts 48 and 49 referred toabove, the change-over switch is fitted with a third contact 58 which,via a wire 59, is connected to a switch 60 that is actuated by a cam 61mounted on drive shaft 26, as well as with a fourth contact 62 which,via a wire 63, is connected to a potentiometer 64 whose adjustablecontact arm, via a wire 65, is connected to one of the two contacts ofswitch 60. Said contact is, via a wire 66, connected to the frame of theapparatus and to a switch 67 that is actuated by a cam 68 mounted onshaft 26. A line 69 leads from switch 67 to an electrically conductivedrum 70, over which punched tape 54 is tracked in such a way that acontact pin'53, which extends through a perforation 55 in the tape,comes into conducting connection with drum 70.

A further cam 71 mounted on shaft 26 actuates the aforesaid doubleswitch 50, and a cam 72 which also is secured to shaft 26, actuates achange-over switch 73 in the supply circuit for the coil of magneticclutch 31. The coil is connected directly to one of the poles 74 of avoltage source, the other pole 75 of which is connected directly to oneof the contacts of change-over switch 73 via a wire 76 and to the othercontact of the change-over switch via a wire 77 that contains a manuallyactuated pulse switch 78. This switch may, for instance, be incorporatedinto the above-mentioned heddling hook or be a foot contact actuated bythe operator.

The apparatus functions as detailed below.

In the rest position, FIGS. 2 and 3, in which cross bar 23 and all theframes 21 are in their right hand extreme position, shaft 26 and cams61, 68, 71 and 72 mounted thereupon assume the positions shown'in FIG.5. The coil of magnetic clutch 31 is de-energized. one" of thecontact'pins 53 associated with a retaining magnet 11 for one of therows of heddles is, via aperfor'ation 55 in punched tape 54, inconducting contact with drum and the current circuit of the associatedmagnet 37 is therefore closed via contact 58, wire 59, switch 60, wire66, switch 67, lines 69, 52, 51 and 47 and contact 49. Thus, theassociated pawl 35 is engaged in recess 33 of the associated driving rod22 and switch 39 is closed. The coil of magnet 1 1 receives current viaa circuit from contact 49 through wire 46, potentiometer 45, lines 44,40 and 38 to the frame which, via wire 66, switch 60 and wire 59 isconnected with contact 58. In this case, the magnetizing current isrelatively weak and its magnitude is dependent upon the position of thecontact arm of potentiometer 45.

When the operator closes pulse contact 78, clutch 31 is energized andshaft 26 begins to rotate. After the shaft has turned a little,changeover switch 73 actuated by cam 72 switches in such a way that theclutch continues-to receive current via line 76 even if contact 78 isreleased. In response to the rotation of shaft 26, cross bar 23 anddriving rods 22 are pushed forward, that is to say towards the left inFIGJ4, and that frame 21, selected by punched tape 54, whose grippermagnet 11 is energized, is moved forward along with the cross bar whilethe other frames 21 with associated arms 10 remain stationary in theposition shown in FIG. 2. As briefly touched upon above, one of arms 12is likewise moved forward so that its magnet 11 carries a drop blade 13with it.

After an initial angular displacement of shaft 26 cam 68 breaks switch67 whereby magnet 37 is deenergized, but since pawl 35, as mentionedabove, is mechanically held in engagement with recess 33, the frame andgripping arm 10 continue their forward movment until clutch 31 is againdisengaged when shaft 26 has rotated approximately 180, when change-overswitch 73 changes to the position shown in FIG. 5. During this part ofthe revolution, switch 67 is closed once more by the second projectionon cam 68 and if punched tape 54 has in the meantime been advanced onestep, a magnetizing circuit for a magnet 37 associated with anotherframe 21 is established hereby so that pawl 35 of said other frameengages with the second recess 34 of the associated driving rod 22. Themagnetizing circuit to the gripper magnet 11 of this other frame is alsoclosed so that a heddle 9 of another weaving shaft isseparated and movedsome distance forward away from the remaining heddles on that weavingshaft. This possibility appears from FIG. 3, in which there are shown infully drawn and dotted lines, respectively, two heddles 9 and 9 whichhave been moved unequal distances away from their respective rows ofheddles, the first heddle being separated when a pawl 35 engages with arecess 34 while the heddle 9', shown with a dotted line, was separatedwhen the associated pawl engaged with a recess 33.

After a very short travel of frame 21 and, hence, gripper magnet 11,roller 42 moves down the inclined surface 43 whereby change-over switch41 connects the coil of the gripper magnet directly via wire 47 tocontact 49 of change-over switch 50. Then the gripper magnet receivesthe fully magnetizing current and hence exerts an increased holdingforce as has been described in the foregoing.

When the operator has drawn a warp thread through each heddle 9 held bya magnet 11 (and, if necessary, also through a drop blade 13), he againactuates switch 78 whereby clutch 31 is engaged once more so that shaft26 continues its rotation back into the starting position shown in FIG.5. During this rotation, frame 21 with arm 10 first moves a shortdistance further towards the left before it reverses and approximatelyat the same time cam 61 breaks switch 60, so that the magnetizingcircuit of retaining magnet 11 is interrupted. Shortly after this, cam71 actuates the double change-over switch 50, whereby the magnetizingcircuit is switched on again, this time, however, via wire 63 andpotentiometer 64. As the direction of the current is reversed now, it isensured that any remanence in magnet 11 will be eliminated. At the sametime the operator may twist arm 10 (in a manner not shown in detail)slightly about its vertical axis, as has been indicated in FIG. 1 forone of arms 10, so that during the return movement, the arm and grippermagnet 11 are clear of heddle 9 which may be manually pushed further tothe side towards the previously drawn-in heddles of the same wearingshaft. Before shaft 26 stops again in the position shown in FIG. 5,change-over switch 50 is again returned to its starting position so thatthe operating sequence can be repeated with the next heddle selected bythe p'unched tape 54 which, in the intervening period, is moved one morestep forward.

It will be understood from the above description that drive motor 30 mayrotate constantly since an electromagnetic clutch has been insertedbetween the motor and shaft 26. It would be possible, however, todispense with the clutch if a so-called stepping motor is used as drivemotor. The two potentiometers 45 and 64 are adjustable from the outsideof the apparatus and can thus be adjusted during operation. In certaincircumstances it will be possible to dispense with potentiometer 64which regulates the value of the demagnetizing current. A similarpotentiometer might be inserted into the common power supply line fromthe input terminals which supply the relatively strong magnetizingcurrent to the magnets 11. If no need exists of separating two heddles(and drop blades) in the same operation, then cam 68 is replaced by acam which is provided with one projection only for actuating switch 67.The stepwise movement of carriage 1 parallel to the weaving shaftsreferred to previously can be controlled by a sensor which bears againstthe edge of warp l5 and which provides a signal for starting the motoreach time a certain number of warp threads have been drawn throughheddles and/or drop blades. However, the carriage may also be moved by apawl mechanism which advances it one step each time a warp thread isdrawn in. Before the operation is initiated, the carriage is positionedso that each magnet 11 is in contact with the foremost heddle in therespective row of heddles. It is also possible to employ the apparatuswhen drawing in warp threads from more than one warp layer and in such acase punched tape 54 may be expediently provided with a correspondingnumber of perforation series with associated contact pins that providecurrent for lamps fitted at the respective warp layers so as to markfrom which layer the'thread has to be taken.

The invention has been described in the foregoing in connection with anapparatus for separating heddles from several rows of heddles and with agripper magnet and associated separate driving means for each row ofheddles so tht only that gripper magnet, which simultaneously receivesmagnetizing current, moves away from the row of heddles. However, itwill also be possible to couple all gripper magnets togethermechanically in such a way that all move away from the respective row ofheddles during each drawing-in operation since the selective energizingof the gripper magnets ensures that only heddles from the selected rowor plurality of rows are transferred. The invention may also be utilizedin connection with an apparatus that has only a single gripper magnetfor operating upon several rows of heddles in which case the magnet willbe moved transversally in through the apertures of the weaving shaftsand, controlled by a programming device or by a patterning device, becaused to stop in register with the selected weaving shaft before it issupplied with magnetizing current to separate a heddle from the shaft inquestion. Subsequent to the termination of the separating operation, themagnet or magnets are again moved clear of the weaving shafts.

Instead of, as shown, being mounted on the ends of their respective arms10, the gripper magnets could be fitted in another position along thearm which position may be adjustable. It would also be possible to havetwo spaced gripper magnets mounted on each arm, for example one at thetop and one at the bottom of the associated row of heddles. The magnetsmay be detachably secured to their arms by means of a mechanical quickconnector which at the same time provides the electrical connectionbetween the magnet coil and the power supply line. Even if the apparatusis described and shown as being mounted above the weaving shafts, itcould also be mounted below these, or there might be provided oneapparatus above and one below the weaving shafts. That part of the framein which the weaving shafts are supported which has not been describedcan, broadly speaking, be constructed as described in US. Pat. No.3,653,106 which is herewith incorporated by reference.

The term weaving members as used in the following claims is to beconstrued as covering both the heddles and drop blades mentioned above.

We claim:

1. An apparatus for individually separating a weaving member having apassage for the drawing in of a warp thread from a row of such weavingmembers and for positioning the weaving member for said drawing-in of awarp thread from a warp through said passage of the weaving member, saidapparatus comprising a gripper electromagnet means for moving saidgripper electromagnet towards and away from said row of weaving membersand means for supplying said electromagnet with a first current duringan initial phase of the movement of the electromagnet away from said rowof weaving members, and with a second magnetizing current during asubsequent phase of said movement, said first current being weaker thansaid second current.

2. An apparatus as claimed in claim 1, comprising separate control meansfor effecting at least substantial de-magnetization of said gripperelectromagnet before its return movement towards the row of weavingmembers commences.

3. An apparatus as claimed in claim 2, in which said first and secondmagnetizing currents are DC currents, and said control means is adaptedto reverse the direction of the current through the magnet coil toeffect demagnetization.

4. An apparatus as claimed in claim 1, wherein said current supply meanscomprises a variable resistor for manually adjusting the value of atleast said first magnetizing current.

5. An apparatus as claimed in claim 1, comprising a frame and drivemeans for reciprocating said frame parallel to the row of weavingmembers, means in said frame for supporting an arm on which said gripperelectromagnet is mounted, said current supply means comprising twoparallel feed lines and a stationary changeover switch adapted toselectively connect the coil of said gripper electromagnet to either ofsaid feed lines and an actuating member mounted in said frame foractuating said change-over switch.

6. An apparatus as claimed in claim 5, comprising a pawl member mountedin said frame for releasably connecting said frame to its drive meansand a switch connected in each of said parallel feed lines and adaptedto be closed by said pawl member when the frame is being connected toits drive means.

7. An apparatus as claimed in claim 6, wherein said drive means for saidframe comprises a drive shaft, drive means for intermittently rotatingsaid drive shaft, first and second cams secured to said drive shaft, andsaid current supply means comprises a switch connected in each of saidparallel feed lines and adapted to be closed by said first cam at leastduring the movement of said frame away from the row of weaving members,a magnet coil mounted in said frame for effecting engagement of saidpawl member and a current feed line for said magnet coil including aswitch actuated by said second cam.

8. An apparatus as claimed in claim 7, comprising a plurality of frameswith associated arms and gripper magnets for separating weaving membersfrom a corresponding number of parallel rows of weaving members, acommon drive mechanism for the reciprocating movement of all the frames,means for locking said pawl member of each frame to said drive mechanismduring reciprocation of that frame, said second cam having two angularlyspaced regions for successively actuating the associated switch, theapparatus further comprising a programming device connecting saidlastmentioned switch to the magnet coil of a frame selected by saidprogramming device, and means for advancing said device one step duringthe period between two successive actuations of the switch.

9. An apparatus as claimed in claim 7, comprising a third cam secured tosaid drive shaft for reversing the polarity of the current through saidgripper electromagnet.

10. An apparatus as claimed in claim 7, comprising a a fourth camsecured to said drive shaft, an electromagof said drive shaft.

1. An apparatus for individually separating a weaving member having apassage for the drawing in of a warp thread from a row of such weavingmembers and for positioning the weaving member for said drawing-in of awarp thread from a warp through said passage of the weaving member, saidapparatus comprising a gripper electromagnet means for moving saidgripper electromagnet towards and away from said row of weaving membersand means for supplying said electromagnet with a first current duringan initial phase of the movement of the electromagnet away from said rowof weaving members, and with a second magnetizing current during asubsequent phase of said movement, said first current being weaker thansaid second current.
 2. An apparatus as claimed in claim 1, comprisingseparate control means for effecting at least substantialde-magnetization of said gripper electromagnet before its returnmovement towards the row of weaving members commences.
 3. An apparatusas claimed in claim 2, in which said first and second magnetizingcurrents are DC currents, and said control means is adapted to reversethe direction of the current through the magnet coil to effectdemagnetization.
 4. An apparatus as claimed in claim 1, wherein saidcurrent supply means comprises a variable resistor for manuallyadjusting the value of at least said first magnetizing current.
 5. Anapparatus as claimed in claim 1, comprising a frame and drive means forreciprocating said frame parallel to the row of weaving members, meansin said frame for supporting an arm on which said gripper electromagnetis mounted, said current supply means comprising two parallel feed linesand a stationary change-over switch adapted to selectively connect thecoil of said gripper electromagnet to either of said feed lines and anactuating member mounted in said frame for actuating said change-overswitch.
 6. An apparatus as claimed in claim 5, comprising a pawl membermounted in said frame for releasably connecting said frame to its drivemeans and a switch connected in each of said parallel feed lines andadapted to be closed by said pawl member when the frame is beingconnected to its drive means.
 7. An apparatus as claimed in claim 6,wherein said drive means for said frame comprises a drive shaft, driVemeans for intermittently rotating said drive shaft, first and secondcams secured to said drive shaft, and said current supply meanscomprises a switch connected in each of said parallel feed lines andadapted to be closed by said first cam at least during the movement ofsaid frame away from the row of weaving members, a magnet coil mountedin said frame for effecting engagement of said pawl member and a currentfeed line for said magnet coil including a switch actuated by saidsecond cam.
 8. An apparatus as claimed in claim 7, comprising aplurality of frames with associated arms and gripper magnets forseparating weaving members from a corresponding number of parallel rowsof weaving members, a common drive mechanism for the reciprocatingmovement of all the frames, means for locking said pawl member of eachframe to said drive mechanism during reciprocation of that frame, saidsecond cam having two angularly spaced regions for successivelyactuating the associated switch, the apparatus further comprising aprogramming device connecting said last-mentioned switch to the magnetcoil of a frame selected by said programming device, and means foradvancing said device one step during the period between two successiveactuations of the switch.
 9. An apparatus as claimed in claim 7,comprising a third cam secured to said drive shaft for reversing thepolarity of the current through said gripper electromagnet.
 10. Anapparatus as claimed in claim 7, comprising a fourth cam secured to saiddrive shaft, an electromagnet clutch in the drive means for said shaft,first and second parallel feed lines for said clutch, said first feedline connecting the magnet coil of the clutch directly to a voltagesource said second feed line including a manually operable switch, achange-over switch for selectively connecting the coil of the clutch toeither of said parallel feed lines, said fourth cam being shaped so asto actuate said switch twice during each revolution of said drive shaft.